For example, in a mobile communication terminal, a plurality of signals having a different frequency band are input into and/or output from a common terminal. In this case, a multiplexer such as a duplexer is used. Japanese Patent Application Publication No. 2013-62556 discloses that a matching circuit is used when filters having a different pass band are connected to a common terminal. The matching circuit controls a reflection coefficient so that a signal of which frequency is different from a pass band of the matching circuit is input into a filter.
However, the matching circuit has a component such as an inductor and/or a capacitor. Therefore, the multiplexer gets larger.